Interim results of the Oxford COVID-19 vaccine trials find that the vaccine protects against symptomatic disease in 70% of cases—with vaccine efficacy of 62% for those given two full doses, and of 90% in those given a half then a full dose (both trial arms pre-specified in the pooled analysis). The results are the first full peer-reviewed efficacy results to be published for any COVID-19 vaccine, and are published in The Lancet.
The vaccine was found to be safe, with only three out of 23,745 participants over a median of 3.4 months experiencing serious adverse events that were possibly related to a vaccine; one in the vaccine arm, one in the control arm, and one in a participant who remains masked to group allocation. All participants have recovered or are recovering, and remain in the trial.
Study author, Dr. Merryn Voysey, University of Oxford, UK, says: "The results presented in this report provide the key findings from our first interim analysis. In future analyses, with more data included as it becomes available, we will investigate differences in key subgroups such as older adults, various ethnicities, doses, timing of booster vaccines, and we will determine which immune responses equate to protection from infection or disease."
